Internal-combustion engine



Nov. 5, 1929 D. J. MARTIN INTERNAL CGMBUSTION ENGINE Filed Nov. 16. 19272 Sheets-Sheet INVENTOR ,U JTJMarfim BY ATTORNEYS WITNESSES D. JKMARTIN11,734,867

INTERNAL CQMBUSTION ENGINE Fil'ed Nov. L6, 1927 2 Sheets-Sheet 2 Nov. 5,1929.

N. N N N P w P w w w H x X WM E E FL. 1E Fr B C D E F G H J K L INVENTORlllMarmm W ATTORNEYS WlTNESSES Nov; 5,

DOUGLAS 3. MARTIN, OE NEW YORK, N. Y., -ASSIGI\TOR T MARTIN MOTORS, INQ,GE NEW YORK, N, Y., A CORFORATION OF DELAWARE INTERNAL-COMBUSTION ENGINEApplication filed November 16, 1927. Serial No. 233,670.

is connected, is in the most effective posi-' tion.

7 A further object is to' provide an engine of the character stated inwhich the crank arm of the drive shaft to which the working piston isconnected is disposed within a sector centering on 90 to an eccentric onthe crank shaft, the strap of said eccentric being to the auxiliarypiston whereby the action of the eccentric and the auxiliary piston hasa lag behind the movement of the working piston.

Thisjengine is adapted for high or low speeds and has many advantagesover the other types of engine, all of which will be more fullyhereinafter described and pointed out in the claim. I

In the accompanying drawings- Figure 1 is a view in longitudinalsection.

of my improved engine, showing the pistons in approximate position forignition of the mixture;

Figure 2 is a fragmentary view taken at right angles to Figure-1 throughthe crank case and a portion of the engine;

' Figures 3, 4, 5 and 6 are diagrammatic views showing the variouspositions of the pistons in the cylinder during the power and 'suctionstroke;

Figure 7 is a diagram'illustrating the movements and operation of thepistons.

I shall first describe the engine illustrated and later set forth theoperation and advantages attained by the engine.

1 represents an engine cylinder having a closed head 2 and at its lowerend secured to a crank case 3 in which a crank shaft 4 18 mounted. Forconvenience of description I shall refer to the upper and lower ends ofthe engine but it is of course to be understood that the engine mayfunction in other positions than in a vertical one and that thislanguage is employed for convenience in describing the engine.

5 and 6 represent inlet and exhaust valves in head and 7 is a spark plugor other means for ignition. In the casing 1 a Working piston 8 isprovided and connected by a connectlng rod or link 9 with a crank arm 10on shaft 4.

Thisworking piston 8 reciprocates within an auxlhary piston 11, thelatter reciprocating freely in the cylinder 1. The auxiliary piston 11is connected at its lower end, and at opposite sides, by links orconnecting rods r 12 with eccentric straps 13 on eccentrics 14 of thecrank shaft 4. w

The crank arm 10 and the eccentrics 14 are disposed within a sectorcentering on an angle of approximately 90 to each other, and this is animportant phase of my invention that will hereinafter be enlarged upon.

The arrangement of pistons and their mountings in the cylinder iscapable of mod ilication, but I have illustrated the auxiliary piston ashaving an annular chamber 15 externally thereof in which inlet andexhaust openings 16 and 17 are provided for the passage of a coolingmedium.

Furthermore, I may provide around the auxiliary piston a spiral or otherweb 17 to strengthen the piston and guide the same in the cylinder.

The lower end of the auxiliary piston is preferably provided with one ormore keyways 18 receiving keys 19 in the cylinder 1 so as per ends ofthe workingpistonS and the auxiliary piston 11 are the same, but this isof course capable of modification, in accordance 'with the resultsdesired.

In this particular case I desire that the auxiliary piston may be eitherof the same area as the working piston or has a movement which willdisplace a volume equal to the displacement of the working piston end,so that as the working piston moves past dead center, which is adownward movement, the auxiliary piston will moveupwardly and maintain avolumetric balance. If the the auxiliary piston displaces a largervolume than the working piston the result will-be a super-compression orpost-compression which may also be accomplished' by a greater movementof the auxiliary piston and this variation in movement is of coursecontrolled by the throw of the co- 2 centrics.

To explain the operation of the engine, attention is called tothe-diagram Figure 7 and also to Figures 3, 4:, 5 and 6 which illustratediflerent ositions of the pistons.

at the left indicates a complete revolution of the crank shaft, thecapital letters indicating the sectors, of movement of the crank arm 10,and the small letters the movement of the eecentrics. The horizontallines extending to the right of the circular diagram indicate the linearmovement of the working piston in a com lete reciprocation and the smalldiagram at t e upper, right-handportion of Figure 86 7 illustrates thelinear movement of the auxiliary piston registering with a smallcircular diagram indicating the movement of the eccentrics.

Also at the central portion of the right- 49 hand circular diagram(Figure 7) thehorizontal lines indicate the linear movement of theauxiliary piston as brought about by the turning movement of theeccentrics.

the extreme of. its upper movement with the crank arm at dead center,and it shows when inthis position that the auxiliary piston issubstantially parallel to the working face of the working piston. I

5o Fi re 4 illustrates the approximate firing positlon, and it will benoted that as the crank arm passes over dead center the working piston'8 moves downwardly at the same time the auxiliary piston movesupwardly, thus maintaining a volumetric balance in the cylinder. v v

' Figure 5 shows the working piston 8 moving downwardly on its powerstroke and it will be noted that during a portion of the downwardmovement of the working piston the auxiliary piston moves upwardly andthen follows downwardly with the stroke of the working piston.

However, it will be noted that the linear movement of the auxiliarypiston is very short Inthe 'agram (Figure'?) the bisected circle ascompared with the movement of the working piston due of course to thethrow of the eccentrics as compared with the throw of the crank arm, butthese movements of the working and auxiliary pistons are exactly timedin accordance with the angular position of the crank arm relative to theeccentrics which will now be explained, reference being had moreparticularly to the diagram in Figure 7 The circle indicating themovement of the crank arm and eccentric in Figure? is, for convenienceof description, divlded into sectors of twenty-two and a'half degreeseach, and the diagram indicates an engine with a pressure balancedthrough twenty-two and a halt degrees.

While the working piston crank turns through the first sector A, theeccentric shown at a 90 lag also turns through a sector of the samesize, indicated by a. The, diagram shows that the working piston falls adistance, indicated by A, and the auxiliary piston rises a distance,indicated by a. A and a are equal and the eccentric circuit may be sodesigned that this equal fall and rise will:

hold good to any desired point of balance.

At top dead center, the working piston and the auxiliary piston are sideby side. As the working piston fallsthrough the distance indicated by A,the auxiliary piston rises through an equal distance, indicated by thecharacter a. 1

As the crank arm turns through the sector .B the working piston falls adistance, indicated by B', and the eccentric turns through the sector band rises a much lesser distance than the working piston, as indicatedat I).

These relative movements can be followed on the diagram through themedium of the letters, the capital letters indicating the sectorsthrough which the crank arm moves and thesmall letters indicate thesectors through which theeccentrics move, the primed capital Figure 3illustrates the working piston at letters indicating the linear movementof the working piston and the'primed small letters of the volumetricbalance and ignition'then' following 1s expansion, continuing) throughthe measures 13, C, D, E' and Fand exhaust through G, H. Y

It is of course to be understood that the tlmlng of the exhaust may bevaried so that -it may be lengthened or shortened, but in any event thisexhaust takes place while this pis ton is at or near its lowest sector.1 i

The capital letters I, J K, L, M, N, O, P, mdicate'the movement of thepiston on its scavenging stroke as well as on its compression stroke,and thls complete reciprocation is of course repeated in a four-cycleengine to draw in the charge and compressit,

as above explained.

In the above description of my invention I apply the termauxiliarypiston to the part 11 and as this piston functions as acompressi'onmember, forming a partaffixed to a tube or sleeve it may also be termeda compression piston, and these terms are used indiscriminately as thepart 11 is in reality both a'piston, a sleeve and a compression member.

An engine such as above described and op erated in the manner stated hasmany advantages some which may be enumerated as follows:

There will be no loss of compression while the piston is passing overdead center.

The compression may either be maintained or increased tosuper-compression or postcompression in ,accorda-nce with the throw ofthe eccentric.

The work of compression and super-compression is divided between thecrank arm and the eccentrics, the working piston and the auxiliarypiston both moving toward the head of the cylinder for compression andfor maintenance of compression. This enables the cutting down of theweight of the individual parts. i

The working piston moves up rapidly and attains the first stage ofcompression and when it'has arrived at a certain pressure the auxiliarypiston or compression piston moves up and increases this pressure to anydesired amount'in accordance 'With the movements imparted to thepistons. Y

The wide number of adjustments of angle, eccentric throw, and of lengthof eccentric connecting rod, permit of any desired adjustment and timingof the pressure balance or pressure boosting function of the tubularcompression piston.

The invention, as shown, achieves a volumetric balance at both ends ofthe stroke when the two pistons are moving in different directionsduring the period .of' equal lifts for equal angles.

It permits of a lowerpower stroke, and gives more time for thefunctioning of the valves, near top and bottom dead center.

When the Working piston is at dead center and beginsto fall in thecylinder, the tubular compression balance piston rises and balances thepressure above the falling working piston to any desired point. In thediagram this is'shown to a point of twenty-two anda half degrees beyonddead center. Then i the balancepiston continues up at a slow rate 'untilit reaches the top of its travel, the working piston, in the meantime,falling rapidly. v

By'increasing the throw of the eccentrics,

'greatercompression may be obtained. or the Attention is called to therelatively large range of compression pressures attainable by arelatively small movement of the tubular compression piston after theworking piston has come to dead center.

A very small increased movement causes a corresponding decrease involume, but at the point where this small decrease in volume means agreat increase in pressure. That is, after the working piston has passeddead center (the point of maximum compression in ordinary gas engines)by the rela tively large angle between the crank and the eccentric, andby adjusting the eccentric throw, and the position and area of thetubular compression piston, I can attain any desired increase incompression.

A further and very important new feature is the fact that the up anddown movement of the tubular compression piston is much less (aboutone-half) of the up and down movement as required in my original patentto'achieve the required balance on an angle of thirty-six degrees, moreor less.

I have referred to the operating parts as a crank arm and eccentric, andI would have it distinctly understood that these terms are used in thebroadest possible sense to include any mechanical means or mechanismwhich Will function for the purpose, as, for example, the eccentricmight constitute a crank arm and other expedients might be resorted to,and I do not wish to be limited to such terminology employed in thespecification or the claim.

, While I have illustrated what I believe to be a preferred embodimentof my invention, it is obvious various changes and alterations might bemade in the general form of the parts described without departing frommy invention and hence I do not limit myself to the precise details setforth but consider myself at liberty to make such changes andalterations as fairly fall within the spirit and scope of the appendedclaim.

I claim:

In an internal combustion engine, the combination with a cylinder and anauxiliary piston in the cylinder, of a working piston within theauxiliary piston, said auxiliary piston having a displacement within thecylinder such that during the period in which the working piston movesfrom the top dead centre to a predetermined ignition position, theauxiliary piston is given an inward displacement through a portion ofits stroke wherein its spee auxiliary plston and its displacementmaintains a predetermined compression condition. Signed at New York, inthe county of New York and State of New York, this 14th day of November,A. D. 1927.

DOUGLAS J. MARTIN.

d is greatest, the arrangementbeing such that the product of the area ofthev

